1. Field of the Invention
This invention generally relates to reflectance photometer instruments for controlled administering of insulin in diabetes management. More particularly, this invention relates to an improved programmable alarm clock circuit specifically adapted for use with such instuments.
2. Description of the Prior Art
Instruments designed for accurate and convenient measurement of blood glucose levels are increasingly being used by diabetics as an integral part of in-home diabetes management programs. A variety of such instruments are commercially available for use by diabetics for monitoring and recording their blood glucose levels and adjusting insulin-administration quantities and schedules in conjunction with appropriate medical supervision.
Such reflectance photometer instruments or glucose monitors typically operate on reflectance or absorption photometry principles for providing an analysis of chemically treated strips which have been coated with blood to be analyzed. Typically, needle or lancet arrangements are provided for extracting an individual's blood. The monitoring individual then coats a chemically-treated reagent strip with the extracted blood and inserts the blood-coated strip, after a predefined reaction time period has elapsed, into the reflectance photometer instrument for photometric analysis of the blood glucose content using electronic sensing circuitry.
The more sophisticated reflectance photometer systems are portable, self-contained systems which include mechanical or electro-mechanical means for extracting blood from an individual and transferring the blood to glucose-sensitive chemical reagent means, and an electronic analysis system which operates under control of a microprocessor and includes photosensing electronics connected to a microcomputer or custom-integrated circuit for analyzing the chemical reagent means for providing an external indication of the measured glucose level. The external indication is generally in the form of a LCD display which can be used by a diabetic for instantaneous insulin-level adjustment. The reflectance photometer systems can also include a provision for maintaining a log of periodically taken glucose readings for purposes of subsequent medical study and treatment. Such microprocessor-based systems are advantageous because of their accuracy of measurement and, particularly, because they can be conveniently programmed to provide a variety of functions in addition to basic blood analysis.
One important peripheral function required of such sophisticated systems is the ability to provide preprogrammed alarm signals for alerting diabetics at predetermined time periods to the need for, inter alia, monitoring glucose levels, receiving an insulin injection, or ingesting requisite food supplements. Conventional microprocessor-based reflectance photometer systems have typically realized this function by (i) the provision of real time clock circuits or chips containing a built-in alarm clock feature or (ii) using the microprocessor itself to generate the alarm signals by powering up the processor at regular intervals and determining whether the instantaneous time corresponds to a stored alarm time.
Major disadvantages with such approaches are the need for high power consumption and the fact that the use of separate clock chips is undesirable due to added expense and bulk, particularly in the case of portable and handheld reflectance photometer instruments where both space and power are at a premium.
Accordingly, there exists a need for providing means for implementing programmable alarm clock functions in microprocessor-based reflectance photometer instruments which is conservative in terms of power requirements, which does not require separate real time clock chips with built-in alarms and external power control circuitry, and is adapted for use with the existing microprocessor circuitry in conventional programmable reflectance photometer instruments.